Log slow checkpoints (mplotqueries --checkpoints)

[mitesh-gosavi]

Expected behavior

mplotqueries —checkpoint flag should provide a scatterplot of all the slow checkpoints along with their duration and timestamp.

Actual/current behavior

mTools does not currently log any slow checkpoints. This issue focuses on logging the slow checkpoints (greater than 1 second). Log lines for slow checkpoints were added as a fix in versions 4.1.12 (For reference, see SERVER-16176). mTools currently skips these lines and does not parse or plot them.

Steps to reproduce the actual/current behavior

mplotqueries —checkpoint flag can be added to the argument parser. The parser on receiving the —checkpoint flag can search for log lines containing the “Checkpoint took” token (for reference, see mongodb/mongo@f3eb442). On encountering the token, the parser can parse the token after “took” and typecast it to an integer to get the duration.

Environment

Software	Version
mtools	1.5.3
MongoDB server	4.0.10